How believable are published laboratory data? A deeper look into system-compliance and elastic modulus

Elastic modulus(E) interpretation is debatable with limited literature detailing the impact of systemcompliance.To address this impact,a comprehensive testing schedule using an aluminium 6061(Al)sample is carried out on several systems under various test setups.Al is chosen as it is extruded and adheres to well defined shape tolerances and elastic properties.A robust method,using the SavitzkyGolay filter,is introduced to identify significant slope changes in the stress-strain curve.Since the load in the test system is well defined,the recorded deformation is corrected to the expected value of Al resulting in a system-compliance factor.The results across the testing systems and test setups showed significant variance,with the recorded E always lower than the anticipated E_(Al).The number of components within the system over which the deformation is measured had the most significant impact,lowering the expected E by up to 50%.Additionally,the system-compliance factor is inconsistent across different systems and setups.Thus,it is evidently proved that each setup must be separately evaluated for its system-compliance and that no single value exists across systems and setups.The findings are then projected onto a series of uniaxial compressive strength(UCS) tests carried out on Stanstead granite(SS GR) samples.The corrected E_(t50) and E_(avg) values for system-compliance of the samples are within ±1%for each system as opposed to being ±50% pre-correction.The findings conclude that it is deemed necessary and of utmost importance that the deformation be corrected to accommodate the systemcompliance to obtain reliable results.     

Proposed Multiply Charged Ion Source

A proposal is presented in this work for a new type of ion source that employs a hyperbolic potential field for the dual purpose of trapping the plasma ions, and permitting the electrons to impact the trapped ions successively, which by turn render the ions highly stripped. The pvwposed souroe consists of an axially symmetric hyperbolic Penning assembly energized with fixed and cosinusoidal voltage and is immersed in a homogeneous axial magnetic field. The anode and both of the two cathodes follow hyperboloid surfaces of one and two sheets respectively. Extraction of the stripped ions can be accomplished either radially or axially through an extracting system, which is optimized to satisfy Pierce conditions of rectilinear flow. Filtering the extracted ions is done by a quadrupole mass analyzer. Under the influence of the imposed hyperbolic potential field, electrons are allowed to ascillate with bound or unbound trajectories depending on the operating conditions. From the solutions of the equations of motion governing such oscillating electrons, it is possible to optimize the overall performance of the proposed ion source.     

Deep learning based approach for digitized herbarium specimen segmentation

Multimedia Tools and Applications - As herbarium specimens are largely digitized and freely available in online portals, botanists aim to examine their taxonomic aspects to identify the plant...     

Road traffic density estimation using microscopic and macroscopic parameters

In this paper we present a comparative study of two approaches for road traffic density estimation. The first approach uses the microscopic parameters which are extracted using both motion detection and tracking methods from a video sequence, and the second approach uses the macroscopic parameters which are directly estimated by analyzing the global motion in the video scene. The extracted parameters are applied to three classifiers, the K Nearest Neighbor (KNN) classifier, the LVQ classifier and the SVM classifier, in order to classify the road traffic in three categories: light, medium and heavy. The methods are compared based on their robustness to the classification of different road traffic states. The goal of this study is to propose an algorithm for road traffic density estimation with a high precision.     

Stabilisation of discrete 2D time switching systems by state feedback control

This article deals with sufficient conditions of asymptotic stability for discrete two-dimensional (2D) time switching systems represented by a model of Roesser type with state feedback control. This class of systems can correspond to 2D state space or 2D time space switching systems. This work is based on common and multiple Lyapunov functions. The results are presented in LMI form. Two examples are given to illustrate the results.     

Nonlinear H ∞ control of a Quadrotor (UAV), using high order sliding mode disturbance estimator

A nonlinear H _∞ output feedback controller is proposed and coupled to a high-order sliding mode estimator to regulate an UAV in the presence of the unmatched perturbations. The plant to be controlled is a Quadrotor helicopter described by nonlinear dynamics with plant uncertainties due to the variations of inertia moments and payload operation. A robust state estimation is considered under model uncertainties as well as external/measurement disturbances. Performance issues of the controller are illustrated in a simulation study made for an UAV prototype.     

Type-2 fuzzy sliding mode control without reaching phase for nonlinear system

A new sliding mode control (SMC) algorithm for the nth order nonlinear system suffering from parameters uncertainty and subjected to an external perturbation is proposed. The algorithm employs a time-varying switching plane. At the initial time t=t₀, the plane passes through the point determined by the system initial conditions in the error state space. Afterwards, the plane moves to the origin of the state space. Since the nonlinear system is sensible to the perturbations and uncertainties during the reaching phase, the elimination of such phase yields in a considerable amelioration of system robustness. Switching plane is chosen such that: (1) the reaching phase is eliminated, (2) the nonlinear system is insensitive to the external disturbance and the model uncertainty from the initial time (3) the convergence of the tracking error to zero. Furthermore, a Type-2 fuzzy system is used to approximate system dynamics (assumed to be unknown) and to construct the equivalent controller such that: (1) all signals of closed-loop system are uniformly ultimately bounded, (2) the problems related to adaptive fuzzy controllers like singularity and constraints on the control gain are resolved. To ensure the robustness of the overall closed-loop system, analytical demonstration using Lyapunov theorem is considered. Finally, a robot manipulator is considered as a real time system in order to confirm the efficiency of the proposed approach. The experimentation is done for both regulation and tracking control problems.     

Synthesis of highly conductive polyaniline nanofibers

Polyaniline nanofiber product synthesized by using both potassium biiodate, KH(IO₃)₂, and sodium hypochlorite oxidant shows high electrical conductivity of greater than 100 S cm^− 1. The nanofiber product also shows not only a long nano-size fibril structure with average diameter of ~ 50 nm and length of ~ 4 μm but also high crystallinity. It was observed that the nanofibers synthesized using the two oxidants give both high electrical conductivity and high crystallinity compared to polyaniline synthesized using commonly known ammonium peroxydisulfate (APS) oxidant. We also found that dimensional and morphological uniformity of PANI nanofibers were greatly improved when the two oxidants were used. The long length and high crystallinity will probably be the contributing factors to have high conductivity. Order of the oxidant addition for the synthesis has no effect on quality of the product. Characterization study was made via UV/Vis absorption spectra, X-ray diffraction (XRD) and scanning electron microscopy (SEM) as well as conductivity measurement.